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Commit a24f9d6c authored by Nathan Huckleberry's avatar Nathan Huckleberry Committed by Sasha Levin
Browse files

riscv/atomic: Fix sign extension for RV64I 

[ Upstream commit 6c58f25e6938c073198af8b1e1832f83f8f0df33 ]

The argument passed to cmpxchg is not guaranteed to be sign
extended, but lr.w sign extends on RV64I. This makes cmpxchg
fail on clang built kernels when __old is negative.

To fix this, we just cast __old to long which sign extends on
RV64I. With this fix, clang built RISC-V kernels now boot.

Link: https://github.com/ClangBuiltLinux/linux/issues/867


Signed-off-by: default avatarNathan Huckleberry <nhuck@google.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 0a39db51

arch/riscv/include/asm/cmpxchg.h

+4 −4
Original line number Diff line number Diff line
@@ -187,7 +187,7 @@ 
			"	bnez %1, 0b\n"				\

			"1:\n"						\

			: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr)	\

			: "rJ" (__old), "rJ" (__new)			\

			: "rJ" ((long)__old), "rJ" (__new)		\

			: "memory");					\

		break;							\

	case 8:								\
@@ -232,7 +232,7 @@ 
			RISCV_ACQUIRE_BARRIER				\

			"1:\n"						\

			: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr)	\

			: "rJ" (__old), "rJ" (__new)			\

			: "rJ" ((long)__old), "rJ" (__new)		\

			: "memory");					\

		break;							\

	case 8:								\
@@ -278,7 +278,7 @@ 
			"	bnez %1, 0b\n"				\

			"1:\n"						\

			: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr)	\

			: "rJ" (__old), "rJ" (__new)			\

			: "rJ" ((long)__old), "rJ" (__new)		\

			: "memory");					\

		break;							\

	case 8:								\
@@ -324,7 +324,7 @@ 
			"	fence rw, rw\n"				\

			"1:\n"						\

			: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr)	\

			: "rJ" (__old), "rJ" (__new)			\

			: "rJ" ((long)__old), "rJ" (__new)		\

			: "memory");					\

		break;							\

	case 8:								\